21425408240 has 20 divisors (see below), whose sum is σ = 49814074344. Its totient is φ = 8570163264.

The previous prime is 21425408233. The next prime is 21425408317. The reversal of 21425408240 is 4280452412.

It is a tau number, because it is divible by the number of its divisors (20).

It is a junction number, because it is equal to n+sod(n) for n = 21425408197 and 21425408206.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 133908722 + ... + 133908881.

Almost surely, 2^21425408240 is an apocalyptic number.

21425408240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21425408240 is an abundant number, since it is smaller than the sum of its proper divisors (28388666104).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21425408240 is a wasteful number, since it uses less digits than its factorization.

21425408240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 267817616 (or 267817610 counting only the distinct ones).

The product of its (nonzero) digits is 20480, while the sum is 32.

The spelling of 21425408240 in words is "twenty-one billion, four hundred twenty-five million, four hundred eight thousand, two hundred forty".